1. Field of the Invention
This invention relates to the control of leakage from ducts, such as fluid-carrying pipework, and aims to provide means to reduce or prevent leakage from apertures compromising the integrity of ducts and attributable to causes such as manufacturing faults or blemishes, rust or other corrosive activity, piercing damage, age of pipework, or joints.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97-1.99
It is usually the case, for one reason or another, that significant areas of fluid-carrying ducts, once installed as part of a pipework system, become substantially inaccessible. For example, mains water distribution systems employ vast lengths of buried pipework which involves expensive and time-consuming excavation to expose, for scrutiny and/or repair, areas of pipe from which leakage is suspected.
An efficient technique for locating leakage without resort to major excavation is thus required, and such a technique is described, for example, in International Patent Application No. PCT/GB 99/03742.
That application describes a technique wherein a sensor means is provided within the pipe for detecting characteristics of the fluid. The detected characteristics are recorded and used to evaluate a fluid flow field characteristic which is compared with a reference fluid flow field characteristic for that pipe to obtain thereby data concerning a leak. The comparison may usefully be effected by means including a neural network.
It is thus known that leakage can be localised without excavation or other expensive investigative techniques. However, it may still be necessary to excavate or otherwise uncover the leaking pipework in order to control the leak, and the present invention seeks to reduce or eliminate the need for such activities.
Moreover, there are occasions, particularly in the oil, gas and nuclear industries, when a rapid response to leakage or to a lack of containment generally) is essential. In addition there is often the need, having stemmed the initial flow of fluid from a leak, to accurately locate the leak so that a permanent repair may be made, or other remedial action taken. Still further, there may be a need in some operational circumstances to shield or protect workers, engaged in the location of leaks and/or the associated repairs, from the leaking fluid.